Without limiting the scope of the present disclosure, its background is described with reference to managing fluid levels within a holding tank used to hold chemical additives for hydraulic fracturing fluid.
During hydraulic fracturing operations, formation rock around a wellbore may be broken up with pressurized fluid to enhance hydrocarbon recovery. As this pressurized fluid is pumped down a well to the location where the fracturing is to occur, various liquid additives may be mixed with that fluid. The liquid additives are typically brought onsite in a tote, such as a portable container on a vehicle, to hold the liquid additives. A chemical transfer pump is then used to pump those chemicals into one or more holding tanks typically located on a skid or truck mounted blender system.
The holding tank typically is in fluid communication with a blender, where the liquid additive is mixed with other components of a hydraulic fracturing fluid. In some configurations, the liquid additive is gravity fed from the bottom of the holding tank to a liquid additive pump that in turn pumps the liquid additive to the blender. During blending operations, the level of the liquid additive within the holding tank will constantly rise and fall as the tank is drained by virtue of the liquid additive pump and replenished by virtue of the chemical transfer pump. In order to ensure that holding tank maintains a continuous supply of liquid additive to the liquid additive pump so as not to cause the liquid additive pump to operate dry, the chemical transfer pump should maintain a minimum supply of liquid additives in the holding tank during blending operations.
Additionally, it is desirable that the holding tank not overflow. During hydraulic fracturing operations, it is possible that an operator of the chemical transfer pump can get distracted by one of the many tasks that have to be performed. If the chemical transfer pump is left off for too long, the holding tank may run dry, potentially causing damage to the liquid additive pump. Conversely, if the chemical transfer pump is left on for too long, the holding tank could overflow, leading to a potential safety hazard.